ChapterSummary
•The female reproductive system is composed of ovaries, fallopian tubes, uterus, cervix, vagina, external genitalia, and mammary glands. The ovaries have 2 regions, the cortex and medulla. The former contain follicles and the latter vascular and neural elements. There are approximately 400,000 follicles at birth, of which approximately 450 reach maturity in the adult. The remaining follicles undergo atresia.
•Maturation involves the formation ofthe primary, secondary, and finally, the Graafian follicle. During ovulation, a rise in antral fluid causes the follicle to rupture. The ovum will degenerate in 24 hours unless fertilized by the spermatozoan. Following ovulation, the follicle changes in the following manner: theca interna cells become theca lutein cells and secrete estrogen;
while follicular cells become granulosa lutein cells, producing progesterone. If the ovum is fertilized, the corpus luteum persists for 3 months, producing progesterone. Its survival is dependent upon human chorionic gonadotropin secreted by the developing embryo. Thereafter, the placenta produces progesterone, required to maintain pregnancy.
•The fallopian tube is divided into the infundibulum, ampulla, isthmus, and interstitial segment. Fallopian tubes are lined by a mucosa containing cilia that beat toward the uterus, except in the infundibulum, where they beat toward the fimbria. Fertilization occurs in the ampulla, which is also the most frequent site of ectopic pregnancies.
•The uterus has 3 coats in itswall:
-The endometrium is a basal layer and superficial functional layer. The latter is shed during menstruation.
-The myometrium is composed of smooth muscle.
-The perimetrium consists of the peritoneal layer of the broad ligament.
The menstrual cycle results in cyclical endometrial changes. The first 3-5 days are characterized by menstrual flow. Thereafter, the proliferative stage commences. During this time, lasting 14 days, the endometrium regrows. This phase is estrogen-dependent. During the secretory phase, the endometrium continues to hypertrophy, and there is increased vascularity. This phase is progesterone-dependent. The premenstrual phase is marked
by constriction of spiral arteries leading to breakdown of the functional layer. Failure offertilization leads to a drop in progesterone and estrogen levels, and degeneration of the corpus luteum about 2 weeks after ovulation.
•The placenta permits exchange of nutrients and removal ofwaste products between maternal and fetal circulations. The fetal component consists of the chorionic plate and villi. The maternal component is decidua basalis.
Maternal blood is separated from fetal blood by the cytotrophoblast and syncytiotrophoblast.
•The vagina contains no glands. It is lined by stratified, squamous epithelium, rich in glycogen. During the estrogenic phase, its pH is acidic. During the postestrogenic phase, the pH is alkaline and vaginal infections could occur.
